A138466 a(1)=1; for n >= 2, a(n) = n - floor((1/2)*a(a(n-1))).

1, 2, 2, 3, 4, 5, 5, 6, 7, 8, 8, 9, 10, 10, 11, 12, 13, 13, 14, 15, 16, 16, 17, 18, 19, 19, 20, 21, 21, 22, 23, 24, 24, 25, 26, 27, 27, 28, 29, 30, 30, 31, 32, 32, 33, 34, 35, 35, 36, 37, 38, 38, 39, 40, 40, 41, 42, 43, 43, 44, 45, 46, 46, 47, 48, 49, 49, 50, 51, 51, 52, 53, 54

Offset

1,2

Links

Table of n, a(n) for n=1..73.

Michel Dekking, Proof by Benoit Cloitre

Formula

For n >= 1, a(n) = floor((sqrt(3)-1)*(n+1)).

Mathematica

Floor[(Sqrt[3] - 1)*(Range[100] + 1)] (* Wesley Ivan Hurt, Jan 20 2024 *)

Prog

(PARI) a(n)=floor((sqrt(3)-1)*(n+1))

Crossrefs

Cf. A005206, A138467, A160390.

Sequence in context: A210357 A057359 A076538 * A247784 A249243 A066530

Adjacent sequences: A138463 A138464 A138465 * A138467 A138468 A138469

Keyword

nonn,easy

Author

Benoit Cloitre, May 09 2008

Status

approved